Guys my evap codes went away and almost immediately i have code P1147 and P0139 which I believe could be the Bank1 rear O2 sensor? Is this easy to replace? how long does it take? Any special tools or does it replace like the one on my trans am did? Just pulls out (via plastic bracket) plug in new one and drive away?

Is the O2 diagnosis the likely cause?

 

Interesting...this is not the first time I've seen EVAP DTCs and O2 DTCs in the same post. They may be related somehow.

FWIW, I used to get P0138 (bad o2), P0455 (gross fuel leak), and P1448 (EVAP control valve open).

I changed my EVAP canister & the control valve and the O2 sensor code has not come back in about 200 miles. Also, it seems all of my long term fuel trims are significantly negative (below -4%, sometimes reaching to -12%).

 

Yeah, but I think if it were specifically canister related I'd still have one of the evap codes, those are completely gone since the new gas cap.

I'm wondering if perhaps the EVAP codes masked the O2 issue? Because it was about a week after I put on the gas cap and cleared the ECU that the O2 issue surfaced...

I'm going to replace the O2 in the next couple weeks, I hope to God its not a canister too